UN Ambassador Susan Rice has faced a second day of questioning over her handling of intelligence in the deadly September 11 attack on the US Consulate in Benghazi, Libya.

Ms Rice continued her fight to win over sceptics in the Senate who could block her chances of becoming the next US Secretary of State.

Republican Senator Susan Collins emerged from discussions with Ms Rice saying she could not support her nomination for the position without more information.

"I continue to be troubled by the fact that the UN Ambassador

She said she was "troubled" the ambassador "played what is essentially a political role" in going on national TV shows to present the Obama administration's position in the middle of the presidential election.

Republican Senators John McCain, Lindsey Graham and Kelly Ayotte emerged from their talks with Ms Rice on Tuesday expressing similar displeasure with the much-criticised initial public explanations about the cause of the September attack.

The US consulate in Benghazi was attacked on September 11

Four Americans died in the assault on the consulate, including US Ambassador Chris Stevens.

Ms Rice conceded to the senators that her initial account five days after the attack - that a spontaneous demonstration over an anti-Muslim video produced in the US triggered it - was wrong, but insisted she had not been trying to mislead the American people.

Her unusual visit to Capitol Hill - typically, only nominees meet privately with lawmakers - reflects the Obama administration's support for her efforts.

Ms Rice is seen as the top candidate for President Barack Obama to nominate to replace Hillary Clinton as Secretary of State.

Republicans, however, have expressed support for Democratic Senator John Kerry, a former candidate for president, as a more likely candidate to replace Mrs Clinton.

Senator Collins told reporters she believed Senator Kerry would have a much easier path to confirmation.

The White House has remained defiant in its support for Ms Rice, arguing that she had no responsibility in compiling the information on the cause of the attack.

House Democrats have suggested that the Republican opposition to Ms Rice, a black woman, is sexist and racist.